In the cultivation of mushroom spawn and fungi, it is known to use containers if the form of polymer recipient in order to hold humid substrate in which the fungi or mushroom spawn is cultivated.
Oxygen is to be allowed to enter into the recipient, being a bag, in order to enable the cultivation of the spawn or fungi.
As the spawn or fungi is very sensitive for microspore contamination, e.g. contamination with germs or bacteria, recipients such as bags made completely from gas permeable but liquid impermeable membranes are known from EP418323. Such material however is quite expensive in use.
Alternative recipients are bags comprising a polymer wall, which is provided with a plurality of openings. The openings are closed by means of filter membranes, usually gas and liquid permeable fibrous material. As an example, a bag is described in EP85928. This bag has the disadvantage that it should not be filled above the level of the filter membrane.
Another alternative recipient, being a bag, is described in EP645078. A polyester bag is provided with a number of openings, which openings are sealed by gas permeable sealing strips, e.g. a strip provided from spun bonded micro porous polyolefin.
It was found that recipients, such as e.g. the bags of EP645078, in spite of the sealing with a micro porous strip, still suffer from contamination with germs, fungi and/or microspores when being filled completely with moist substrate.